PORTSMOUTH — A planned search dive by New Hampshire Fish and Game began at 11:30 a.m. on Tuesday morning in hopes of finding the body of a missing University of New Hampshire student.

Prescott Park and Peirce Island were closed off to the public while, Associate Attorney General of New Hampshire Jane Young said, Marine Patrol are on the water, State Police are in the air and now Fish and Game are diving to find Elizabeth “Lizzi” Marriott, a 19-year-old from Westborough, Mass.

Twin brothers, Perry and Conrad McKinney, 70, have also been contributing to the search for Marriott's body, combing the shoreline for at least a week.

Perry McKinney runs the boat launch at Peirce Island and Conrad McKinney is a private detective. The twins said they feel compelled to assist in the search. They know the inlets and coves well because they grew up in Portsmouth.

“We'll be out here for a long time,” Conrad McKinney said. “We're doing the areas you can't see from a plane or get to with a boat. We're just looking for anything out of the ordinary.”

He added, “It's a tragedy for the parents. I can't imagine what they're going through.”

Marriott has been missing since Oct. 9. Seth Mazzaglia, 29, of Dover, was arrested on Oct. 13 and charged with killing Marriott. He was arrested the day after police searched his Sawyer Mills apartment in Dover and is charged with second-degree murder facing a probable cause hearing on Monday. He is currently being held without bail at Strafford County House of Corrections. Officials believe he either strangled or suffocated Marriott, though investigators have not revealed the evidence pointing them in this direction.